// Vercel Serverless Function — replaces the Apps Script webhook.
// Handles the same request shapes your website already sends:
//   { type: 'custom_email', to, subject, body }        — Send Email + Campaigns
//   { type: 'email_reply', to, subject, subjectHint, body }  — Reply mode
//   { ...registration fields, no type }                 — new registration -> shortlisting email
//
// Required Vercel Environment Variables (Project Settings -> Environment Variables):
//   GMAIL_USER          your Gmail address, e.g. admin@nikkahpathways.com.au
//   GMAIL_APP_PASSWORD  the 16-character App Password from your Google Account
//                        (Google Account -> Security -> 2-Step Verification -> App Passwords)
//
// Only requests from these origins are allowed to trigger a send. Add any
// other domain you actually serve the site from (e.g. a github.io URL you
// test with) to this list.
const ALLOWED_ORIGINS = [
  'https://nikkahpathways.com.au',
  'https://www.nikkahpathways.com.au',
];

const ADMIN_EMAIL = process.env.GMAIL_USER || 'admin@nikkahpathways.com.au';

let nodemailer;
let _transporter;
function getTransporter() {
  if (!_transporter) {
    nodemailer = require('nodemailer');
    _transporter = nodemailer.createTransport({
      service: 'gmail',
      auth: {
        user: process.env.GMAIL_USER,
        pass: process.env.GMAIL_APP_PASSWORD,
      },
    });
  }
  return _transporter;
}

function applyCors(req, res) {
  const origin = req.headers.origin;
  if (ALLOWED_ORIGINS.includes(origin)) {
    res.setHeader('Access-Control-Allow-Origin', origin);
  }
  res.setHeader('Access-Control-Allow-Methods', 'POST, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type');
}

module.exports = async (req, res) => {
  applyCors(req, res);

  if (req.method === 'OPTIONS') {
    res.status(200).end();
    return;
  }
  if (req.method !== 'POST') {
    res.status(405).json({ status: 'error', message: 'Use POST' });
    return;
  }

  const data = req.body || {};

  try {
    if (data.type === 'custom_email') {
      await sendCustomEmail(data);
      res.status(200).json({ status: 'ok' });
      return;
    }

    if (data.type === 'email_reply') {
      await sendReplyEmail(data);
      res.status(200).json({ status: 'ok' });
      return;
    }

    if (data.type === 'questionnaire' || data.type === 'questionnaire_reminder_legacy') {
      // Nothing to do — the site already writes questionnaire completion
      // straight to Firestore itself.
      res.status(200).json({ status: 'ok' });
      return;
    }

    if (data.type === 'questionnaire_reminder') {
      await sendQuestionnaireReminderEmail(data);
      res.status(200).json({ status: 'ok' });
      return;
    }

    // Default: a new registration -> send the shortlisting email immediately.
    await sendShortlistingEmail(data);
    res.status(200).json({ status: 'ok' });
  } catch (err) {
    console.error('send-email error:', err);
    res.status(500).json({ status: 'error', message: err.message });
  }
};

async function sendCustomEmail(data) {
  if (!data.to) throw new Error('Missing recipient email');
  const htmlBody = String(data.body || '').replace(/\n/g, '<br>');
  await getTransporter().sendMail({
    from: `"Nikkah Pathways" <${ADMIN_EMAIL}>`,
    to: data.to,
    replyTo: ADMIN_EMAIL,
    subject: data.subject || 'Message from Nikkah Pathways',
    html: htmlBody,
  });
}

async function sendReplyEmail(data) {
  if (!data.to) throw new Error('Missing recipient email');
  // Nodemailer can only send, not search/read Gmail — so unlike the Apps
  // Script version, this can't find and reply inside an existing thread.
  // It sends a fresh email with "Re: " on the subject, which Gmail's own
  // heuristics will usually (not always) still group with the original
  // conversation.
  const subject = data.subjectHint ? `Re: ${data.subjectHint}` : (data.subject || 'Re: Your message');
  const htmlBody = String(data.body || '').replace(/\n/g, '<br>');
  await getTransporter().sendMail({
    from: `"Nikkah Pathways" <${ADMIN_EMAIL}>`,
    to: data.to,
    replyTo: ADMIN_EMAIL,
    subject,
    html: htmlBody,
  });
}

async function sendQuestionnaireReminderEmail(data) {
  if (!data.email) throw new Error('Missing recipient email');
  const name = data.name || '';
  const city = data.city || 'the event';
  const link = data.link || 'https://nikkahpathways.com.au/questionnaire.html';
  const subject = 'Reminder — Please Complete Your Nikkah Pathways Questionnaire';

  const html = `<div style="font-family:Arial,sans-serif;max-width:600px;margin:auto;color:#333;font-size:15px;line-height:1.7">
  <div style="background:#1a1a2e;padding:30px;text-align:center;border-radius:8px 8px 0 0">
    <h1 style="color:#fff;margin:0;font-size:22px">Nikkah Pathways</h1>
    <p style="color:#c9a96e;margin:4px 0 0;font-size:14px">${city} Event</p>
  </div>
  <div style="background:#fff;padding:30px;border:1px solid #e5e5e5">
    <p>Assalamu Alaykum <strong>${name}</strong>,</p>
    <p>Just a friendly reminder to complete your matchmaking questionnaire — it helps us find your best matches inshallah:</p>
    <div style="text-align:center;margin:30px 0">
      <a href="${link}" style="background:#c9a96e;color:#1a1a2e;padding:14px 32px;border-radius:6px;text-decoration:none;font-weight:bold;font-size:16px;display:inline-block">
        Complete the Questionnaire →
      </a>
    </div>
    <p>Questions? Reply to this email or WhatsApp us at <strong>0488 885 770</strong>.</p>
  </div>
  <div style="background:#1a1a2e;padding:20px;text-align:center;border-radius:0 0 8px 8px">
    <p style="color:#fff;margin:0"><strong>The Nikkah Pathways Team</strong></p>
    <a href="mailto:${ADMIN_EMAIL}" style="color:#c9a96e;text-decoration:none">${ADMIN_EMAIL}</a>
  </div>
</div>`;

  await getTransporter().sendMail({
    from: `"Nikkah Pathways" <${ADMIN_EMAIL}>`,
    to: data.email,
    replyTo: ADMIN_EMAIL,
    subject,
    html,
  });
}

async function sendShortlistingEmail(data) {
  const name = (data.fname && data.lname) ? `${data.fname} ${data.lname}`.trim() : (data.name || '').trim();
  const email = (data.email || '').trim();
  const city = (data.city || data.eventCity || data.event_city || '').trim();
  const eventDate = data.date || data.eventDate || 'TBC';
  const timeDisplay = data.eventTime || 'Time to be confirmed';
  const venueDisplay = data.eventVenue || 'Venue to be confirmed';

  if (!email || !city) {
    console.warn('Skipped shortlisting email — missing email or city.', { email, city });
    return;
  }

  const subject = "You've Been Shortlisted for Nikkah Pathways!";

  const html = `<div style="font-family:Arial,sans-serif;max-width:600px;margin:auto;color:#333;font-size:15px;line-height:1.7">
  <div style="background:#1a1a2e;padding:30px;text-align:center;border-radius:8px 8px 0 0">
    <h1 style="color:#fff;margin:0;font-size:22px">Nikkah Pathways</h1>
    <p style="color:#c9a96e;margin:4px 0 0;font-size:14px">${city} Event</p>
    <p style="color:#c9a96e;margin:6px 0 0;font-size:14px">A halal and supportive space for hearts to meet</p>
  </div>
  <div style="background:#fff;padding:30px;border:1px solid #e5e5e5">
    <p>Assalamu Alaykum <strong>${name}</strong>,</p>
    <p>Thank you for registering for the <strong>Nikkah Pathways ${city} Event</strong>.</p>
    <div style="background:#fff8ee;border-left:4px solid #c9a96e;padding:16px 20px;border-radius:4px;margin:20px 0;text-align:center">
      <p style="font-size:20px;margin:0;font-weight:bold;color:#1a1a2e">Congratulations — you've been shortlisted!</p>
    </div>
    <h2 style="color:#1a1a2e;border-bottom:1px solid #e5e5e5;padding-bottom:8px">Event Details</h2>
    <table style="width:100%;font-size:15px">
      <tr><td style="padding:6px 0;width:130px"><strong>City</strong></td><td>${city}</td></tr>
      <tr><td style="padding:6px 0"><strong>Venue</strong></td><td>${venueDisplay}</td></tr>
      <tr><td style="padding:6px 0"><strong>Date</strong></td><td>${eventDate}</td></tr>
      <tr><td style="padding:6px 0"><strong>Time</strong></td><td>${timeDisplay}</td></tr>
      <tr><td style="padding:6px 0"><strong>Cost</strong></td><td>$150 per person</td></tr>
      <tr><td style="padding:6px 0"><strong>Meals</strong></td><td>Included</td></tr>
    </table>
    <p style="background:#f5f5f5;padding:12px 16px;border-radius:4px;font-size:14px">
      Female attendees are encouraged to bring a <strong>mahram</strong>. A <strong>$100 mahram fee</strong> applies.
    </p>
    <h2 style="color:#1a1a2e;border-bottom:1px solid #e5e5e5;padding-bottom:8px">To Secure Your Spot</h2>
    <p>Please make payment within <strong>48 hours</strong>:</p>
    <div style="background:#f9f9f9;border:1px solid #e0e0e0;border-radius:6px;padding:16px 20px">
      <p style="margin:4px 0"><strong>Account Name:</strong> Ilyas Aden</p>
      <p style="margin:4px 0"><strong>BSB:</strong> 182-182</p>
      <p style="margin:4px 0"><strong>Account Number:</strong> 031453087</p>
      <p style="margin:4px 0"><strong>Reference:</strong> <span style="color:#c9a96e;font-weight:bold">NP ${city} - ${name}</span></p>
    </div>
    <h2 style="color:#1a1a2e;border-bottom:1px solid #e5e5e5;padding-bottom:8px">Important Notes</h2>
    <ul style="padding-left:20px;font-size:14px;color:#444;line-height:2">
      <li>Spots cannot be held beyond <strong>3 days</strong> without payment</li>
      <li>Full refund within <strong>1 week</strong> of date confirmation</li>
      <li>This is <strong>not an official invitation</strong> — sent after payment received</li>
    </ul>
    <p>Please <strong>reply with your payment receipt</strong> to confirm your booking.</p>
  </div>
  <div style="background:#1a1a2e;padding:20px;text-align:center;border-radius:0 0 8px 8px">
    <p style="color:#fff;margin:0"><strong>The Nikkah Pathways Team</strong></p>
    <a href="mailto:${ADMIN_EMAIL}" style="color:#c9a96e;text-decoration:none">${ADMIN_EMAIL}</a>
    <p style="color:#888;font-size:12px;margin-top:8px">WhatsApp: 0488 885 770</p>
  </div>
</div>`;

  const text = `Assalamu Alaykum ${name},

Thank you for registering for the Nikkah Pathways ${city} Event.

Congratulations — you've been shortlisted!

────────────────────────────
EVENT DETAILS
────────────────────────────
City:     ${city}
Venue:    ${venueDisplay}
Date:     ${eventDate}
Time:     ${timeDisplay}
Cost:     $150 per person
Meals:    Included

Female attendees are encouraged to bring a mahram.
A $100 mahram fee applies.

────────────────────────────
TO SECURE YOUR SPOT
────────────────────────────
Please pay within 48 hours:

Account Name:   Ilyas Aden
BSB:            182-182
Account Number: 031453087
Reference:      NP ${city} - ${name}

────────────────────────────
IMPORTANT
────────────────────────────
- Spots cannot be held beyond 3 days without payment
- Full refund available within 1 week of date confirmation
- This is not an official invitation — sent after payment received

Please reply with your payment receipt to confirm your booking.

Warm regards,
The Nikkah Pathways Team
${ADMIN_EMAIL}`;

  await getTransporter().sendMail({
    from: `"Nikkah Pathways" <${ADMIN_EMAIL}>`,
    to: email,
    replyTo: ADMIN_EMAIL,
    subject,
    text,
    html,
  });

  console.log('Shortlisting email sent to:', name, `(${email})`);
}

{
  "name": "nikkah-pathways-email",
  "version": "1.0.0",
  "private": true,
  "dependencies": {
    "nodemailer": "^6.9.14"
  }
}